Polybrominated diphenyl ethers and bromophenols in paired serum, hair, and urine samples of e-waste dismantlers: Insights into hair as an indicator of endogenous exposure

Polybrominated diphenyl ethers (PBDEs) are important pollutants during dismantling activities of electronic waste (e-waste) in China due to its large production and usage. Bromophenols (BPs), which are a kind of flame retardants and diphenyl ether bond cleavage metabolites of PBDEs, are often neglected in the assessment of human exposure to e-waste. Herein, 22 PBDEs and 19 BPs were determined in paired serum, hair, and urine samples collected from workers and residents of a typical e-waste dismantling site in southern China. Both PBDE and BP congeners were more frequently detected in hair than serum and urine samples. The medians of ΣPBDEs and ΣBPs were 350 and 547 ng/g dw in hair internal (hair-In) of occupational population, respectively, which were significantly higher than non-occupational population. However, a non-significant difference was found in levels of ΣPBDEs and ΣBPs in serum and urine between occupational and non-occupational populations, suggesting that hair analysis could easily differentiate between the exposure intensities of PBDEs and BPs to populations than serum and urine analyses. Moreover, levels of BPs in hair-In were 1-2 orders of magnitude higher than those in hair external (hair-Ex), while a non-significant difference was found in the levels of PBDEs. This result indicated that BPs might have originated from endogenous contribution. Notably, as the predominant congeners, the level of 2,4,6-tribromophenol (2,4,6-TBP) in hair-In was 3-8 times higher than that of BDE-209, while level of 2,4,6-TBP in hair-Ex was 1-3 times lower than that of BDE-209. Furthermore, in vivo experiments performed on Sprague-Dawley rats following a 28-day oral treatment with BDE-209 and 2,4,6-TBP verified that endogenous accumulation of 2,4,6-TBP in hair could be attributed to the metabolism of BDE-209 and exposure to 2,4,6-TBP. In conclusion, compared with PBDEs, biomonitoring phenolic compounds or metabolites with hair could better reflect human endogenous exposure.